In recent years, the pharmaceuticals industry has devoted significant resources to finding ways to cut the time required for identification and validation of lead drug candidates. Disciplines that have arisen to address this need include high-throughput screening and combinatorial chemistry. Using combinatorial methods, libraries made up of large numbers of compounds are randomly or semi-randomly synthesized,then evaluated using high-throughput screening, looking for biological activity or chemical reactions. The availability of solid-phase supports, e.g., resin beads, balls, disks or tubes, for organic synthesis has contributed significantly to the ability to create large combinatorial libraries, making it possible to synthesize a unique compound on each support. Encoding of the solid support enables individual labeling of each compound and tracking of the compound's reaction history. Examples of tagging and tracking techniques as described in U.S. Pat. Nos. 5,770,455 and 5,961,923, both assigned to the assignee of the present application, the disclosures of which are incorporated herein by reference. Such tagging and/or tracking capabilities permit discrete compound split-and-pool synthesis, allowing thousands to millions of compounds to be generated at a time while keeping track of the history of each uniquely synthesized compound throughout the synthesis and subsequent cleaving operations. However, while synthesis and tracking are facilitated by solid phase methods, analysis of the compound or its intermediates may, for many tests requires removal of the synthesized compounds from their solid phase carriers, such that individualized cleavage and concentration of each compound becomes essential. Furthermore, for generation of commercial libraries, it would be preferable to provide the compounds in a convenient form that would require the purchaser to do minimal additional processing in order to perform subsequent assays or other analyses, i.e., following cleaving from the solid support and concentration of the compound. Thus, automated cleavage, concentration and collection of the compounds in a manner that significantly reduces the bottleneck in an otherwise high-throughput process, which allows the compounds to be readily tracked, and which avoids loss of material or cross-contamination between compounds, is an important step in achieving the goals of rapid drug discovery and development.
Solid phase methods have similarly been applied for analysis of biological compounds. Generally, solid phase oligonucleotide synthesis involves covalently attaching the base building block to a solid support such as controlled pore glass (CPG), polystyrene-copolymer, polyester, silica gel, polyamide/Kieselguhr, charged nylon, glass fiber, nitrocellulose or cellulose paper, then synthesizing the oligonucleotide by placing the solid support in a reaction vessel with excess protected nucleosides and coupling reagents. After completion, the oligonucleotide is cleaved from the solid support then deprotected, after which the appropriate analysis can be performed. Such methods have been adapted for purification of DNA, which typically involves the selective elution of impurities by exposing the biological sample to a number of reagents and incubating at elevated temperatures The sample remains attached to the solid support throughout the purification steps then, if desired, the sample can be cleaved from the solid support. DNA purification 15 procedures often require a combination of hazardous reagents, physical force (centrifuge, air pressure or vacuum), lengthy incubation periods and high temperatures (100° C.), which can require special containers and equipment that may not be well suited for very high throughput operations. For example, see International Patent Application No. WO99/13976 of Gentra Systems, Inc., which discloses an automated apparatus for isolating DNA, in which biological samples are combined with solid supports in a sample processing container, wash solution is dispensed into the containers and drained a number of times, then the sample containers are loaded onto a purification apparatus, e.g., a centrifuge. After completion of the purification step, the sample processing container is removed and moved to the next station for cleavage (elution) of the purified sample from the solid support. Thus, while the method disclosed in the referenced PCT application is automated, there is still a significant amount of handling and moving of the samples and sample containers required to complete the purification and elution process.
Systems are known for performing cleavage, elution, concentration, purification, and/or collection of multiple samples, both chemical and biological, however, such systems are not easily integrated into a single processing system that enables the handling of a large number of samples to be cleaved, concentrated and collected automatically. For example, the centrifugal system for vacuum concentration of biological specimens disclosed in U.S. Pat. No. 5,334,130 enables treatment of multiple biological samples within the centrifuge chamber. Cleavage of the compounds from their supports is effected by pouring a typically caustic cleaving agent into each vial before placing the vials into the centrifuge chamber. The chamber is sealed and heated to accelerate cleavage. After cleavage is complete, the concentration step occurs during which the chamber is evacuated and the centrifuge rotor is activated to evaporate the cleaving agent. The rotor speed can sometimes be selected to minimize “bumping”, which can cause solid or liquid form material be propelled out of the vial due to violent outgassing caused by boiling of the solvent. In the system disclosed in the '130 patent, the rotor has a number of holder positions, each of which includes a pressure relief valve for its corresponding vial, thus limiting the number of sample-containers, and consequently, the number of samples, to the number of holder position.
An important aspect of streamlining the process for synthesis, cleavage and concentration of compounds involves establishing a system that allows the compounds to be processed through multiple process steps without frequent transfer of the solid supports and/or compounds from one container to another as needed to allow a certain piece of equipment to be used. However, in the described systems, unless prior processing steps were also performed in the sample containers, transfer into such containers would be required before the cleavage and concentration procedure could be performed. Thus, the cleavage/concentration steps would become rate-limiting in a high-throughput process for several reasons which include: (1) additional handling of the samples is required to place them in the containers; (2) the often-hazardous cleavage agent must be introduced into the container, then the container carefully carried to the centrifuge chamber for loading; and (3) the cleavage and concentration steps are performed as separate procedures.
For the reasons described above, there remains a need for a system for processing of samples on solid supports, which may include cleavage, transfer/collection and/or concentration, that allows for a highly automated method of reagent delivery, cleaving, transfer and/or concentration of a large number of chemical or biological samples in a rapid, cost effective manner.